"""
This file contains default functions applied to a data-frame/dataset as pre/post processing jobs. 
The functions are organized in a pipeline i.e the data will be applied to each function 

Custom functions :
    functions must tak 2 arguments (_data,_args) : where _data is a data frame and _arg is a object describing the input parameters
"""
import pandas as pd
import numpy as np
from datetime import datetime, timedelta


def limit(_data,size):
    """
        ...,{limit:size}
    """
    
    # size = int(_args['limit'])
    return _data.iloc[:size]
def format(_data,_schema):
    """
    This function enforces a schema against a data-frame, this may or may not work depending on the persistence storage
    :_data  data-frame containing all data
    :_args  schema to enforce the data, we are expecting the format as a list of {name,type,description}    
    """   
    return _data 

def approximate(_data,_args):
    """
    :_args  Object of {field:type}
    This function will approximate n-fields in the data given it's distribution
    """
    _m = {'int':int,'float':float,'integer':int,'double':float}
    columns = list(_args.keys())
    for _name in columns :
        if _name not in _data :
            continue
        otype = _args[_name]
        otype = str if otype not in _m else _m[otype]
        _data.loc[:,_name] = np.random.uniform(_data[_name].values).astype(otype)
        
    return _data
def split_date(_data,_args):
    """
    This function takes a field and applies the format from other fields
    :_data  data-frame
    :_config    configuration entry {column:{format,column:format,type}}
    """
    _columns = list(_args.keys())
    _m = {'int':int,'float':float,'integer':int,'double':float}
    for _name in _columns :
        _iname = _args[_name]['column']
        _iformat = _args[_name]['format']['in']
        _oformat = _args[_name]['format']['out']
        _otype = str if 'type' not in _args[_name]  else _args[_name]['type']
        _data.loc[:,_name] = _data[_iname].apply(lambda _date: datetime.strftime(datetime.strptime(str(_date),_iformat),_oformat)).astype(_otype)
    return _data
def newdate(_data,_args):
    """
    This function creates a new data on a given column from another 
    :_data  data frame
    :_args  configuration column:{format,column}
    """
    _columns = list(_args.keys())
    for _name in _columns :
        
        format = _args[_name]['format']
        ROW_COUNT = _data[_name].size
        if 'column' in _args[_name] :
            srcName = _args[_name]['column']
            years = _data[srcName].values
        else:
            years = np.random.choice(np.arange(datetime.now().year- 90,datetime.now().year),ROW_COUNT)
        _data.loc[:,_name] = [ _makedate(year = years[_index],format = format) for _index in np.arange(ROW_COUNT)]
        
    return _data
def _makedate(**_args):
    """
    This function creates a new date and applies it to a column
    :_data  data-frame with columns
    :_args  arguments for col1:format
    """
    _columns = list(_args.keys())
   
    # if _args['year'] in ['',None,np.nan] :
    #     year = np.random.choice(np.arange(1920,222),1)
    # else:
    #     year = int(_args['year'])
    year = int(_args['year'])
    offset = _args['offset'] if 'offset' in _args else 0
    month   = np.random.randint(1,13)
    if month == 2:
        _end = 28 if year % 4 != 0 else 29
    else:
        _end = 31 if month in [1,3,5,7,8,10,12] else 30
    day = np.random.randint(1,_end)

    #-- synthetic date
    _date = datetime(year=year,month=month,day=day,minute=0,hour=0,second=0)
    FORMAT =  '%Y-%m-%d'
    
    if 'format' in _args:
        FORMAT = _args['format']
    

    # print ([_name,FORMAT, _date.strftime(FORMAT)])
    r = []
    if offset :
        r = [_date.strftime(FORMAT)]
        for _delta in offset :
            _date = _date + timedelta(_delta)
            r.append(_date.strptime(FORMAT))
        return r
    else:
        return _date.strftime(FORMAT)